1. Technical Field
The present invention relates to methods of localizing lesions. More specifically, the present invention relates to methods of localizing lesions using radioactive seeds. The invention also relates to techniques and methods for reducing or eliminating migration of radioactive seeds after placement.
2. Background Art
Localization of non-palpable lesions for biopsy or excision during surgery is a necessary procedure. Several techniques are currently available. As described herein, these techniques have several disadvantages and improved methods are needed.
Mammography is credited with the detection of clinically occult cancer of the breast at greater than 80% sensitivity. Since breast biopsies increase the overall cost of screening for breast cancer and 70% of the detected lesions are benign, there is controversy regarding the cost effectiveness of such biopsies. Therefore, the development of more effective biopsy techniques is a significant goal.
There are three different ways to biopsy occult breast lesions. These include “core-needle” biopsy, “ABBI” (Advanced Breast Biopsy Instrumentation), fine needle aspiration biopsy, and open surgical excision biopsy. Open surgical excision biopsy, using needle localization, has been the standard for diagnosis of non-palpable lesions in the breast for the past 20 years.
Although needle localized breast biopsy (NLBB) has some advantages, it has several disadvantages. It requires highest-level skill in placement by radiologists. The method requires flexible wires which are difficult for surgeons to palpate. Currently used wires may be dislodged during transfer of the patient, or displaced from the site of the radiographically located suspicious lesion. When cut inadvertently with scissors, the wires may leave metal fragments in the patient's breast, which has resulted in litigation. A potential for thermal injury to the breast exists when electrocautery is used near the wire. If the insertion site of the wire is too far from the lesion, there is a dilemma in planning the incision to include both the wire and the lesion. This situation can lead to removing more breast tissue than necessary. There are increased costs related to additional x-rays which are used to confirm that the lesion has been excised, longer operating room time fees, specimens require transfer to radiology by operating room personnel, taking a film of the specimen by a radiology technician and finally interpretation and notification by a radiologist.
Recently, several patents have issued pertaining to devices and methods for the removal of lesions from soft tissue. However, these patents do little to overcome the problems detailed above. Specifically, U.S. Pat. No. 5,807,276 to Russin, issued September 1998, discloses a device and method for using a K-wire which is positioned through the lesion to be removed. This device requires that selectable wires are used which can be difficult to maneuver and may cause infection if not properly sterilized.
U.S. Pat. No. 5,833,627 to Shmulewitz et al., issued November 1998, also discloses a needle or cannula of a biopsy device for insertion into the tissue. This is accomplished by correlating, in real-time, the actual needle or cannula position with its probable trajectory once inserted. There is a large amount of speculation involved in the insertion of the needle into the breast or other soft tissue, thus increasing the possibility of removing more soft tissue than is necessary.
Finally, U.S. Pat. No. 5,855,554 to Schneider et al., issued January 1999, discloses support plates which contain the breast. The plates include grids with reference markers for localization and windows for allowing the physician access to the breast. A thick biopsy plate containing a plurality of holes fits into the grid opening through which the biopsy needle is inserted. Again, the same problems pertaining to the insertion of wires or needles can occur which can lead to the removal of excess breast tissue.
Where core biopsy or fine needle aspiration biopsy is performed and cancer diagnosed, there still remains a need for a localized excision of the known cancer and a requirement for localization and removal of the cancer to clear margins.
Although the above discussed biopsies are done for the diagnosis of cancer, it is imperative that physicians treat the lesions as if they are malignant until it is histologically proven otherwise. Lesions should be removed by the most direct approach, as opposed to tracking the lesion and needle through breast tissue. The surgeon also needs to be aware of the placement of the incision so that if a mastectomy is necessary in the future, the biopsy scar can be cleanly excised.
It is therefore desirable to develop a method whereby mammographically detected lesions can be localized and excised in a safe, expeditious, and cost effective manner with the application of current technologies. It is further desirable that the methods for localizing a lesion be stable and minimally migratory within tissues.